The invention relates to a device for taking liquid from a reservoir by inward suction with simultaneous filtration. Such a device is intended to deliver, for example, water from solid constituents before drinking it. This will be necessary in particular when there is a need for drinking-water while pure tap water is not present. In general this may arise with soldiers in the field during manoeuvres or in wartime conditions, or also when citizens live in primitive circumstances. In order to be able to provide for the need for drinking-water in such emergency situations, one often has to resort to contaminated surface water. Purification or sterilisation preceding filtration of the drinking-water then is recommendable. This may be done, for example, by chlorinating a quantity of water, preferably collected in a reservoir, for example, a case-bottle, by means of a suitable chlorinating agent, in which organic impurities are converted into harmless constituents by oxidation, and then removing the excess of chlorine by means of a suitable dechlorinating agent, preferably sodium thiosulphate in a solid condition. Besides, an adsorption with active carbon is usually carried out, while coagulation and/or flocculation under the influence of coagulation and or flocculation agents, sedimentation, and the like may also be necessary. The agents and optionally auxiliary substances to be used for the purification of the water are usually available in the form of a water purification set or -kit which can simply be used by the user himself. For that purpose, the various constituents of the set are added simultaneously or successively to the quantity of water which is to be purified, for example, the quantity of water in a case-bottle. It will be obvious that after purification the water comprises a large quantity of solid constituents which have to be removed before the water may be consumed. These solid consitituents can most simply be removed by filtration.
The invention relates more in particular to a device for sucking liquid from a reservoir, comprising a flexible tube having at one end a filtering unit, which can be immersed in the liquid through an opening in the reservoir, and having a mouthpiece at its other end. Such a device has long been known and is suitable indeed for the above use, viz. for taking liquid from a reservoir by inward suction with simultaneous filtration. An example of such a device, albeit for a slightly different purpose, is shown in FIG. 11 of French Patent Specification No. 1307555: a straw having a small filter at its lower end and intended for sucking liquid.
The disadvantage of this known device is the lack of any provision to carry with himself the device for long periods of time under varying and often unhygienic circumstances without the hygienic condition of the interior of the device being lost and/or the utility of the device being adversely influenced. Moreover, in particular under unfavourable conditions the easy handleability and usability of this device leave to be desired.
It is the object of the present invention to provide a device for sucking liquid from a reservoir with simultaneous filtration of said liquid, which device is very simple and hence can be manufactured in large numbers at a low price, which device can be handled and used easily even upon use under difficult circumstances and which does not have the above disadvantage.
This object can be achieved by means of a device of the type mentioned in the opening paragraph, comprising a flexible tube having at one end a filtering unit which can be immersed in the liquid through an opening in the reservoir, and having a mouthpiece at its other end, which device according to the invention is characterized in that the mouthpiece is connected to the tube in a sealing manner via a flexible hollow member which forms an internal connection between tube and mouthpiece, and that before use of the device the mouthpiece may be enveloped hygienically by a detachable protective cap. Such a protective cap is, albeit for a completely different device, viz. a water purification system comprising a tube having in addition to a filtering agent a bactericidal agent and an adsorbent material accomodated therein, known from patent application No. WO 82/00256. The water purification system described herein, however, has various disadvantages: relatively bulky and thus more difficult to carry by the potential user, rather expensive and, what is most difficult, due to the packing of the tube offering a relatively great resistance to the user during inward suction of liquid.
The device according to the invention does not have these disadvantages. After removal of the protective cap, if any, the flexible hollow member allows easy gripping of the mouthpiece with the mouth, after which the liquid to be drunk can be sucked via filtering unit and tube. As a matter of fact, before use of the device the hollow member is kept in a more or less compressed condition when using a protective cap. After removing said cap, the mouthpiece is moved in the direction of the user's mouth as a result of the flexibility of the hollow member. In addition the flexibility of the hollow member which forms the connection between mouthpiece and tube facilitates the sucking of the liquid from a reservoir which usually has a narrow opening, for example, a case-bottle. This is the more prominent since such devices for sucking liquid often have to be used under extremely unfavourable circumstances as they may occur, for example, for soldiers during manoeuvres or warlike operations.
The device may become contaminated during use. It is, therefore, advisable to dispose of the device after the reservoir, for example, the case-bottle, has been emptied. Consequently, the device according to the invention may be regarded in particular as a so-called "disposable".
It is advantageous to shape the mouthpiece in such way that over at least a part of its length it tapers outwards in the direction of the open front end remote from the tube. This improves the "grip" for the teeth. The mouthpiece is manufactured from a resilient or non-resilient material, for example, from a suitable synthetic material.
In a favourable embodiment of the device according to the invention, the flexible hollow member connecting the mouthpiece and the tube is in the form of bellows. Prior to using the device, the mouthpiece can readily be accomodated inside the detachable protective cap because the bellows-like member can be compressed to a very small size and hence occupies little space. When using the device, the mouthpiece automatically moves towards the user as a result of the flexibility of the bellows-like member, after which the user, with his mouth on the mouthpiece, can easily pull the bellows-like member further outwards and can such the liquid with his mouth from the reservoir via filter and tube. Such a bellows-like member is preferably manufactured from a suitable synthetic material, for example, a suitable polyethylene.
The flexible tube, also termed suction tube, is preferably manufactured from a suitable rubber, for example, silicone rubber. The filtering unit may be connected to the tube in a sealng manner via a mounting aid, for example, from a synthetic material or metal. For that purpose, the aid may be equipped with a tubular part having a slightly larger outside diameter than the tube around which the end of the tube can be slid. On the other side the aid is connected sealingly to the filtering unit in a manner dependent on the nature of the filtering material used. Filters of filtering paper, synthetic material foil or filter cloth may be used, preferably supported by a filter holder, but filters of non-deformable materials are to be preferred, because these materials are least vulnerable. Filters of this latter type, for example, filters of sintered glass, sintered metal or metal gauze, or sintered or porous synthetic material may be connected to the aid, for example, by clamping, gluing or cementing.
For structural reasons from a technical point of view it is to be preferred to connect the flexible hollow member to the tube by means of a connection maens which externally comprises a radially outwardly projecting collar having an upright circumferential edge facing the mouthpiece. Such an upright edge is particularly suitable for the sealing but detachable connection of the protective cap. Both the connection means and the protective cap are preferably manufactured from a non-deformable material, for example, a suitable, non-deformable synthetic material, in which, however, at least one of the adjoining parts of protective cap and connection means (upright edge) has sufficient resilience to ensure a good sealing. In this latter embodiment the upright circumferential edge of the collar of the connection means preferably has an outside diameter which is smaller than the cross-section of the opening in the reservoir, for example, the case-bottle, while the end of the circumferential edge facing the mouthpiece comprises a radially outwardly projecting flange having a larger outside diameter than said opening in the reservoir. In this manner it is prevented that the whole device, the mouthpiece included, can arrive in the reservoir. In addition, the reservoir, for example the case-bottle, can be gradually emptied by drinking (sucking), while between each consumption the device according to the invention remains enclosed in the case-bottle which is closed, for example, by means of a screw cap. In a further preferred embodiment the device according to the invention is constructed so that the protective cap comprises a rod-shaped member which extends axially in the cap and which, in the condition in which the protective cap encloses the mouthpiece, fits in the open front end of the mouthpiece. This embodiment presents the advantage that the mouthpiece and the flexible hollow member connected thereto are firmly and immovably enclosed within the protective cap and cannot be damaged even in the case of a very rough manipulation of the device.
The device according to the invention may also comprise a means for allowing use with a gas mask having a drinking facility, so that, when the device is used by a soldier in the field, the soldier can such water from the case-bottle by means of the device on wearing the gas mask. Such a drinking facility for a gas mask generally comprises a rubber tube provided with a filter or valve, which tube ends within the gas mask in a mouthpiece and is provided outside the gas mask with a nipple for a connection to a valve in the screwing cap of a case-bottle. To also allow use by a soldier in the field on wearing a gas mask having such a drinking facility, the device of the invention according to a different, equally favourable embodiment is characterized in that around the flexible hollow member, which, if desired, comprises a single unitary structure with the tube, is mounted so as to be axially slidable a funnel-shaped member, having a narrow end and a larger portion, the narrow end fitting around the flexible hollow member in a clamping manner and facing the filtering unit, the larger portion, facing the mouthpiece, having an external diameter smaller than the opening in the reservoir and comprising at its end edge a radially outwardly extending flange having a larger circumference than the opening in the reservoir. The last-mentioned embodiment may naturally also be used by a person without wearing a gas mask as described hereinbefore for the previously mentioned embodiment, the tapering mouthpiece offering a good "grip" to the teeth of the user. Upon use by a soldier in the field wearing a gas mask having a drinking facility, the device according the invention in the last-mentioned embodiment can be used by shifting the funnel-shaped member as far as possible over the flexible hollow member in the direction of the mouthpiece until said mouthpiece is in sealing connection with the inner wall of the funnel-shaped member, by then introducing the device with the filtering unit downwards through the opening in the reservoir containing liquid, particularly a case-bottle filled with water to be filtered, until the flange rests on the upper edge of the case-bottle, and by finally closing the case-bottle with the screw cap provided with a valve. The device has now been locked completely within the case-bottle and upon inward suction of liquid from the case-bottle this liquid can reach the mouth cavity of the user only through filtering unit, tube, flexible hollow member and mouthpiece.
To guarantee a good sealing between mouthpiece and funnel-shaped member it is advantageous that the funnel-shaped member for a part of its internal length tapers outwards in the direction of the mouthpiece, at least a portion of its tapering inner surface corresponding with the outside surface of the mouthpiece to allow sealing by the mouthpiece after axial shift relative thereto. When sucking water from an air-tight closed case-bottle a sub-atmospheric pressure is generated in the case-bottle. This can be compensated by the user by blowing air through the device into the case-bottle; by dosing this also solid particles, which may clog the filtering unit, are blown away from the outside of the filter. However, it may also be advantageous to aerate the case-bottle automatically, when used by a person without wearing a gas-mask; in that case the device according to the invention is the last-mentioned embodiment is preferably constructed so that the narrow end of the funnel-shaped member for only a part of its inner surface fits closely around the flexible hollow member, as a result of which longitudinal apertures remain between both members to allow aeration of the reservoir upon use of the device.